This invention relates to promoter sequences and promoter control element sequences which are useful for the transcription of polynucleotides in a host cell or transformed host organism.
The introduction of genes into plants has resulted in the development of plants having new and useful phenotypes such as pathogen resistance, higher levels of healthier types of oils, novel production of healthful components such as beta-carotene synthesis in rice. An introduced gene is generally a chimeric gene composed of the coding region that confers the desired trait and regulatory sequences. One regulatory sequence is the promoter, which is located 5′ to the coding region. This sequence is involved in regulating the pattern of expression of a coding region 3′ thereof. The promoter sequence binds RNA polymerase complex as well as one or more transcription factors that are involved in producing the RNA transcript of the coding region.
The promoter region of a gene used in plant transformation is most often derived from a different source than is the coding region. It may be from a different gene of the same species of plant, from a different species of plant, from a plant virus, an algae species, a fungal species, or it may be a composite of different natural and/or synthetic sequences. Properties of the promoter sequence generally determine the pattern of expression for the coding region that is operably linked to the promoter. Promoters with different characteristics of expression have been described. The promoter may confer broad expression as in the case of the widely-used cauliflower mosaic virus (CaMV) 35S promoter. The promoter may confer tissue-specific expression as in the case of the seed-specific phaseolin promoter. The promoter may confer a pattern for developmental changes in expression. The promoter may be induced by an applied chemical compound, or by an environmental condition applied to the plant.
The promoter that is used to regulate a particular coding region is determined by the desired expression pattern for that coding region, which itself is determined by the desired resulting phenotype in the plant. For example, herbicide resistance is desired throughout the plant so the 35S promoter is appropriate for expression of an herbicide-resistance gene. A seed-specific promoter is appropriate for changing the oil content of soybean seed. An endosperm-specific promoter is appropriate for changing the starch composition of corn seed. A root-specific promoter can be important for improving water or nutrient up-take in a plant. Control of expression of an introduced gene by the promoter is important because it is sometimes detrimental to have expression of an introduced gene in non-target tissues. For example, a gene which induces cell death can be expressed in male and/or female gamete cells in connection with bioconfinement.
One of the primary goals of biotechnology is to obtain organisms, such as plants, mammals, yeast, and prokaryotes having particular desired characteristics or traits. Examples of these characteristics or traits abound and may include, for example, in plants, virus resistance, insect resistance, herbicide resistance, enhanced stability or additional nutritional value. Recent advances in genetic engineering have enabled researchers in the field to incorporate polynucleotide sequences into host cells to obtain the desired qualities in the organism of choice. This technology permits one or more polynucleotides from a source different than the organism of choice to be transcribed by the organism of choice. If desired, the transcription and/or translation of these new polynucleotides can be modulated in the organism to exhibit a desired characteristic or trait. Alternatively, new patterns of transcription and/or translation of polynucleotides endogenous to the organism can be produced.